In the United States, it is estimated that approximately five million people have congestive heart failure (“CHF”). CHF is a life threatening condition that is managed by treating patients with drugs or implantable medical devices such as pacemakers and implantable cardioverter defibrillators (“ICD”). The information obtained through monitoring can be used to diagnose and treat a patient's condition.
Current ICDs and pacemakers have the ability to non-invasively communicate a patient's physical data and programmable parameters with a device such as an external programmer. The programmer is used to interrogate or program the ICD or pacemaker using a wireless, radio frequency telemetry link. Typically, a physician or medical professional utilizes the programmer, while the patient is in the medical office, to access data stored by the ICD or pacemaker, check and adjust on programmed parameters and the like. The programmer can also be used to instruct the ICD or pacemaker to execute desired functions, such as monitoring, stimulating, and storing diagnostic or other data. Conventional programmers in the marketplace allow numerous different parameters to be programmed. The ability to exchange data via a wireless link also permits the health care provider to reprogram or reconfigure the implantable device as required from time to time due to changes in the patient's condition. Recently, implantable devices have been proposed that allow a patient to operate certain types of home-based programmers to interrogate the implantable device in the privacy of the patient's own home. Heretofore, patients have been able to use the home-based programmers at any time to interrogate the implantable device.
However, home-based programmers present the opportunity for undue interrogation of the implantable device, and thus excessive drain on a battery of the implantable device. A power supply, typically a specialized battery, is housed within the implantable device to provide the electrical energy required for operation over an extended length of time. One difficulty is the efficient use of electrical energy. The lifetime of the battery depends on the power demands of the implantable device. For instance, implantable devices that require high speed and long range telemetry require greater battery power. ICDs also require a battery to operate at low current drains for long periods of time and simultaneously provide high current pulses. For example, the normal lifetime of a battery may be five years. To provide the longest battery life, it is desirable to reduce the power consumption required for the various functions of the implantable device. Because replacing a battery requires surgery, it is preferable that the battery last as long as possible.
Most implantable devices are configured to support interrogation by medically trained professionals in a medical office. Most implantable devices do not have the capability of allowing the patient to perform the interrogation at home, and therefore, there is not as great a concern with the drainage of battery power. However, as implantable devices are manufactured to include the feature of allowing a patient to interrogate the implantable device, additional power concerns emerge. Specifically, if a patient does not judiciously interrogate the device, for example if the patient checks the implantable device every few minutes, a heavy power drain on the battery will result. This, in turn, will affect the ability of the implantable device to communicate required patient data as well as affect the operation of the implantable device. Depletion of battery power will potentially lead to early failure of the implantable device and require the battery to be replaced more frequently.
A need remains for an improved implantable device including electrical circuitry and programmable features to limit the number of interrogations performed by a patient in a home environment in order to extend battery life.